1. Field of the invention
The present invention relates to prosthetic restorations which are used on an abutment tooth, and also relates to a method for manufacturing the prosthetic restorations.
2. Description of the Prior Art
There are known prosthetic restorations which are used by being attached to an abutment tooth which has been formed by grinding down a living tooth. These prosthetic restorations are used by being bonded to and fixed on the abutment tooth with a dental cement.
Both (1) metals such as gold, silver and stainless steel and (2) ceramics such as zirconia, aluminia and sapphire have been used as structural materials for such prosthetic restorations.
However, prosthetic restorations made of ceramic materials have a disadvantage in that they have lower toughness and therefore are liable to be damaged.
Furthermore, prosthetic restorations made of noble metals such as gold and silver are very expensive. Moreover, prosthetic restorations made of stainless steel have poor biocompatibility, so that it is concerned about that they may have an adverse effect on the body such as the onset of metal allergies or the risk of carcinogenic actions due to the elusion of Ni and Cr in particular.
In view of the problems as described above, prosthetic restorations made of Ti (titanium) have been developed in recent years. Ti is light and very strong and has excellent corrosion resistance, and it does not give rise to adverse effects due to eluting materials such as those described above.
However, Ti itself does not have so good biocompatibility, and its adhesive property with respect to the abutment tooth is poor. Thus, there is a problem in that a prosthetic restoration made of Ti is liable to be disengaged due to decreasing of the fixing strength. Moreover, prosthetic restorations made of Ti also exhibit poor adhesive onto the outer surface of the prosthetic restoration, so that there is another problem in that peeling off or damage to the coating layer is liable to occur.